Primitive Docker network mode helpers for `RustUse`.
This crate models `bridge`, `host`, `none`, `service:<name>`,
`container:<name>`, and named network values.
```rust
use use_docker_network::DockerNetworkMode;
let mode: DockerNetworkMode = "service:web".parse()?;
assert!(mode.is_service_reference());
assert_eq!(mode.to_string(), "service:web");
```